From 9c1e8a4ebcc04226cb6f3a1bf1d72f4cafd6b089 Mon Sep 17 00:00:00 2001 From: Lubomir Rintel Date: Tue, 10 Mar 2009 12:55:54 -0700 Subject: [PATCH] intel-agp: fix a panic with 1M of shared memory, no GTT entries When GTT size is equal to amount of video memory, the amount of GTT entries is computed lower than zero, which is invalid and leads to off-by-one error in intel_i915_configure() Originally posted here: http://bugzilla.kernel.org/show_bug.cgi?id=12539 http://bugzilla.redhat.com/show_bug.cgi?id=445592 Signed-off-by: Lubomir Rintel Cc: Lubomir Rintel Cc: Dave Airlie Reviewed-by: Eric Anholt Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/char/agp/intel-agp.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/char/agp/intel-agp.c b/drivers/char/agp/intel-agp.c index c7714185f831..4373adb2119a 100644 --- a/drivers/char/agp/intel-agp.c +++ b/drivers/char/agp/intel-agp.c @@ -633,13 +633,15 @@ static void intel_i830_init_gtt_entries(void) break; } } - if (gtt_entries > 0) + if (gtt_entries > 0) { dev_info(&agp_bridge->dev->dev, "detected %dK %s memory\n", gtt_entries / KB(1), local ? "local" : "stolen"); - else + gtt_entries /= KB(4); + } else { dev_info(&agp_bridge->dev->dev, "no pre-allocated video memory detected\n"); - gtt_entries /= KB(4); + gtt_entries = 0; + } intel_private.gtt_entries = gtt_entries; }